High-low pass effect – Adobe After Effects CS4 User Manual
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USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
Voices
The number of voices in the processed (wet) audio.
Modulation Rate
The rate in Hz at which the modulation cycles.
Modulation Depth
The amount of modulation.
Voice Phase Change
The modulation phase difference in degrees between each subsequent voice. Divide 360 by the
number of voices to find the optimum value.
Invert Phase
Inverts the phase of the processed (wet) audio, emphasizing more of the high frequencies; not inverting
the phase emphasizes more of the low frequencies.
Stereo Voices
Alternates assignment of voices to one of the two channels so that the first voice appears in the left
channel, the second in the right channel, the third in the left, and so on. To hear stereo voices, preview or render in
stereo.
Dry Out, Wet Out
The amounts of the original (dry) sound and delayed (wet) sound in the final output. Values of 50%
are commonly used.
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High-Low Pass effect
The High-Low Pass effect sets a limit above or below which frequencies can pass. High Pass allows frequencies above
the limit and blocks frequencies below. Conversely, Low Pass allows frequencies below the limit and blocks frequencies
above. Use High-Low Pass to do the following:
•
Enhance or attenuate (reduce) a sound. For example, using High Pass can reduce traffic noise, which often is
concentrated at low frequencies, while minimally affecting a voice recording. Using Low Pass can remove high-
frequency sounds, such as static and buzzing.
•
Change the focus from one sound to another over time. For example, in audio that contains both music and voice,
you can fade out the music while gradually bringing in the voice.
•
Protect equipment from potentially damaging frequencies.
•
Direct certain frequencies to specific equipment. For example, use Low Pass to isolate sounds intended for a
subwoofer.
To check the frequencies that you filter out, switch to the opposite Filter Options value and preview audio.
Cutoff Frequency
All frequencies below (High Pass) or above (Low Pass) are removed. If the unwanted sound changes
over time, animate this property.
To identify the frequencies of unwanted sound, use the Audio Spectrum effect.
Dry Out, Wet Out
The amounts of the original (dry) sound and delayed (wet) sound in the final output. Common
values for removing frequencies are 0% for Dry Out and 100% for Wet
Out.
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